Can round steel be used as the material for the pipe thread threads of pressure vessels?
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Non-standard pressure vessel, with a pressure of 6 MPa and a temperature of 200°C. Can the pipe thread connections for pressure vessels (with a diameter of 30 mm or less) be manufactured by turning round steel? I heard that round steel cannot be used as pressure-bearing components in pressure vessels. However, some specifications of thick-walled pipes are not available; the minimum diameter for forged round bars is 130, and it’s a waste to machine threads with a diameter of less than 30. What material is used to machine the pipe threads on pressure vessel fittings?
Clause 5.1.8 of the material section of GB/T150.2-2011 permits the use of round steel for manufacturing tubes, but with certain conditions; it is best to follow these requirements. If they are not met, it is recommended to use forged parts instead. If it’s a waste, then it is; meeting the standards is what should be considered first.
Thank you for your reply. My threaded rod material is 304 or 316L; it’s not possible to find small-sized forgings. Buying forged round bars with a diameter of φ130 and then machining them to a φ30 diameter results in too high costs. I would like to ask you another question regarding clause 5.2.9 of GB150.2: \"It is permitted to use steel rods of grades S30408, S30403, etc., with a diameter not exceeding 50 mm as specified in GB/T1220, to manufacture connectors.\" a) The wall thickness of the steel pipe shall not exceed 8 mm, and it shall be used in the solution-treated state. ” Why can’t the wall thickness of steel pipes be greater than 8 mm? Generally speaking, the thicker the wall thickness, the higher the pressure resistance, right?
I’m not aware of that; the standards-setting body also didn’t explain why it was decided in that way.
Forgings are used for processing. The use of pipes is generally not recommended.